Little php error problem

hello,

I want to have custom content between comments. Something like this:
( https://wordpress.stackexchange.com/questions/251219/additional-content-every-x-comments )

I am trying to incorporate this functionality into generatepress theme but from an hour I can't find my mistake

I created a custom plugin, created 3 custom fields named 1,2,3 and then replaced

wp_list_comments( array( 
	'callback' => 'generate_comment'
) );

with

wp_list_comments( array( 
	'callback' => 'generate_comment'
	'_inject_content' => [ get_field('1'), get_field('2'), get_field('3') ]
) );

What's wrong with my php code?

I added this code (which should show content between comments but then all comment section disapeared)

Thanks for any suggestions.